A hyperbolic decay of subjective probability of obtaining delayed rewards

<p>Abstract</p> <p>Background</p> <p>Hyperbolic discounting of delayed and probabilistic outcomes has drawn attention in psychopharmacology and neuroeconomics. Sozou's evolutionary theory proposed that hyperbolic delay discounting may be totally attributable to aversion to a decrease in subjective probability of obtaining delayed rewards (SP) which follows a hyperbolic decay function. However, to date, no empirical study examined the hypothesis, although this investigation is important for elucidating the roles of impatience, precaution, and uncertainty aversion in delay discounting processes.</p> <p>Methods</p> <p>In order to (i) determine the functional form of the relation between delay until receipt and SP, and (ii) examine whether delay discounting is attributable to a decrease in SP, we assessed the subjects' SP and their delay and probability discounting. We examined the fitness of hyperbolic and exponential functions to the assessed SP, and relations between the SP, and delay/probability discounting, and subjective-probability discounting for delayed rewards.</p> <p>Results</p> <p>The results demonstrated (a) SP decayed hyperbolically as delay increases, (b) a decay of SP was associated with delay discounting, and (c) subjective-probability discounting did not significantly correlate with delay discounting.</p> <p>Conclusion</p> <p>Our results demonstrated (i) hyperbolic decay of SP is related to delay discounting, and (ii) delay discounting is, however, not attributable to precautious foresight in intertemporal choice. Further, a novel parameter of pure time preference is proposed.</p

Oxytocin modulates responses to inequity in dogs

Although several animals respond negatively to inequity, the underlying neurochemistry of the process remains poorly understood. In this study, we tested whether the neuropeptide oxytocin mediates responses to inequitable outcomes in domestic dogs (Canis familiaris). Subjects exchanged tokens to receive a food reward in conditions in which the distribution of reward varied. Dogs did respond negatively to inequity, refusing to participate in the test when their partner was rewarded and they were not. Their responses could not be explained merely by frustration, since the presence of a partner being rewarded had a significant effect on their behavior, compared to when the partner was present but not rewarded. Furthermore, after oxytocin intake dogs were less sensitive to the inequitable distribution of reward, performing more successful trials than when administered with placebo. Further, oxytocin treatment also increased dogs’ attention towards their partners, and slowed their decision times, but did not affect their affiliation level toward their partners or the experimenter. Together, our findings suggest that oxytocin modulates responses to inequity in dogs by potentially affecting decision-making processes, but not by increasing affiliation

Head Rubbing and Licking Reinforce Social Bonds in a Group of Captive African Lions, Panthera leo

AbstractMany social animals have a species-specific repertoire of affiliative behaviours that characterise individualised relationshipswithin a group. To date, however, quantitative studies on intragroup affiliative behaviours in social carnivores have beenlimited. Here, we investigated the social functions of the two most commonly observed affiliative behaviours in captiveAfrican lions (Panthera leo): head rubbing and licking. We conducted behavioural observations on a captive group of lionscomposed of 7 males and 14 females, and tested hypotheses regarding three social functions: tension reduction, socialbonding, and social status expression. Disproportionately frequent male–male and female-to-male head rubbing wasobserved, while more than 95% of all licking interactions occurred in female–female dyads. In accordance with the socialbond hypothesis, and in disagreement with the social status expression hypothesis, both head rubbing and lickinginteractions were reciprocal. After controlling for spatial association, the dyadic frequency of head rubbing was negativelycorrelated with age difference while licking was positively correlated with relatedness. Group reunion after daily separationdid not affect the frequencies of the affiliative behaviours, which was in disagreement with the predictions from the tensionreduction hypothesis. These results support the social bond hypothesis for the functions of head rubbing and licking.Different patterns of affiliative behaviour between the sexes may reflect differences in the relationship quality in each sex orthe differential predisposition to licking due to its original function in offspring care

Spatial-Importance-Based Computation Scheme for Real-Time Object Detection From 3D Sensor Data

Three-dimensional (3D) sensor networks using multiple light-detection-and-ranging (LIDAR) sensors are good for smart monitoring of spots, such as intersections, with high potential risk of road-traffic accidents. The image sensors must share the strictly limited computation capacity of an edge computer. To have the computation speeds required from real-time applications, the system must have a short computation delay while maintaining the quality of the output, e.g., the accuracy of the object detection. This paper proposes a spatial-importance-based computation scheme that can be implemented on an edge computer of image-sensor networks composed of 3D sensors. The scheme considers regions where objects exist as more likely to be ones of higher spatial importance. It processes point-cloud data from each region according to the spatial importance of that region. By prioritizing regions with high spatial importance, it shortens the computation delay involved in the object detection. A point-cloud dataset obtained by a moving car equipped with a LIDAR unit was used to numerically evaluate the proposed scheme. The results indicate that the scheme shortens the delay in object detection

Regional gray matter volume in the posterior precuneus is associated with general self-efficacy

Motivation in doing a task is influenced not only by the expected outcome of the task, but also by the belief that one has in successfully executing the task. Over time, individuals accumulate experiences that contribute to a general belief in one’s overall ability to successfully perform tasks, which is called general self-efficacy (GSE). We investigated the relationship between regional gray matter volume and individual differences in GSE. Brain anatomy was analyzed using magnetic resonance images obtained from 64 healthy right-handed participants who had completed Sherer’s GSE scale. After controlling for other factors related to motivation, age, sex, and total gray matter volume of each subject, results showed that regional gray matter volume in the posterior part of the precuneus significantly and positively correlated with GSE score. These results suggest that one’s accumulated experiences of success and failure, which contribute to GSE, also influence the anatomical characteristics of the precuneus